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1687 Publications visible to you, out of a total of 1687
Metagenomic Analysis Using Phylogenetic Placement—A Review of the First Decade

Abstract

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Authors: Lucas Czech, Alexandros Stamatakis, Micah Dunthorn, Pierre Barbera

Date Published: 26th May 2022

Publication Type: Journal

Entity-based Neural Local Coherence Modeling

Abstract (Expand)

In this paper, we propose an entity-based neural local coherence model which is linguistically more sound than previously proposed neural coherence models. Recent neural coherence models encode the … input document using large-scale pretrained language models. Hence their basis for computing local coherence are words and even sub-words. The analysis of their output shows that these models frequently compute coherence on the basis of connections between (sub-)words which, from a linguistic perspective, should not play a role. Still, these models achieve state-of-the-art performance in several end applications. In contrast to these models, we compute coherence on the basis of entities by constraining the input to noun phrases and proper names. This provides us with an explicit representation of the most important items in sentences leading to the notion of focus. This brings our model linguistically in line with pre-neural models of computing coherence. It also gives us better insight into the behaviour of the model thus leading to better explainability. Our approach is also in accord with a recent study (O’Connor and Andreas, 2021), which shows that most usable information is captured by nouns and verbs in transformer-based language models. We evaluate our model on three downstream tasks showing that it is not only linguistically more sound than previous models but also that it outperforms them in end applications.

Authors: Sungho Jeon, Michael Strube

Date Published: 22nd May 2022

Publication Type: InProceedings

Stereoinversion of tetrahedral p -block element hydrides

Abstract (Expand)

The potential energy surfaces of 15 tetrahedral p-block element hydrides were screened on the multireference level. It was addressed whether stereoinversion competes against other reactions, such as … reductive H2-elimination or hydride loss, and if so, along which pathway the stereomutation occurs. Importantly, stereoinversion transition structures for the ammonium cation (C4v) and the tetrahydridoborate anion (Cs) were identified for the first time. Revisiting methane’s Cs symmetric inversion transition structure with the mHEAT+ protocol revealed an activation enthalpy for stereoinversion, in contrast to all earlier studies, which is 5 kJ mol−1 below the C–H bond dissociation enthalpy. Square planar structures were identified lowest in energy only for the inversion of AlH4−, but a novel stepwise Cs-inversion was discovered for SiH4 or PH4+. Overall, the present contribution delineates essentials of the potential energy surfaces of p-block element hydrides, while structure–energy relations offer design principles for the synthetically emerging field of structurally constrained compounds.

Authors: Lukas M. Sigmund, Christopher Ehlert, Ganna Gryn’ova, Lutz Greb

Date Published: 21st May 2022

Publication Type: Journal

Premelting Anomalies in Pyromellitic Dianhydride: Negative Thermal Expansion, Accelerated Radiation Damage, and Polymorphic Phase Transition

Abstract (Expand)

We have established a comprehensive approach to evaluate the structure–property relationships in solid pyromellitic dianhydride (PMDA) at high temperature. Synchrotron single-crystal X-ray diffraction … experiments have yielded structural models for this volatile compound up to 250 °C. PMDA exhibits negative thermal expansion around 145 °C, which is correlated to geometrical changes in the intermolecular carbonyl–carbonyl interactions. A reversible phase transition above ca. 210 °C was detected by differential scanning calorimetry and is associated with the lowering of the molecular symmetry, as indicated by Raman spectroscopy. X-ray powder and single-crystal diffraction data confirm the formation of a new high-temperature monoclinic phase, with two symmetry-independent anhydride groups in the asymmetric unit. The influence of pyromellitic acid impurities on the formation temperature of the new phase has been investigated, and thermodynamic parameters of pure pyromellitic dianhydride have been revaluated. Additionally, the analysis of the temperature- and time-dependent variations in the diffraction patterns allowed us to track the augmented radiation-driven decarboxylation upon heating. Significantly, the formation of a high-temperature low-symmetry phase in PMDA may challenge the solid-state polymerization that aims for highly oriented materials.

Authors: Tomasz Porȩba, Marcin Świa̧tkowski, Michelle Ernst, Giorgia Confalonieri

Date Published: 5th May 2022

Publication Type: Journal

Improving coreference resolution with word formation

Abstract

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Authors: Wei Zhao, Kevin Mathews, Haixia Chai

Date Published: 5th May 2022

Publication Type: InProceedings

A proposal for explicit word formation annotation in discourse corpora

Abstract

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Author: Mark-Christoph Müller

Date Published: 5th May 2022

Publication Type: InProceedings

Towards Effortless Navigation of Scientific-Literature Screen Reading for Biocuration

Abstract

Not specified

Authors: Sucheta Ghosh, Wolfgang Müller, Ulrike Wittig, Maja Rey

Date Published: 5th May 2022

Publication Type: InProceedings

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